We have found that the determination of thiodiglycolic acid (TDGA) in urine may help to characterize metabolic imbalance of substances participating in methionine synthesis, which leads to hyperhomocystinuria. From the metabolic scheme, based on a proper combination of known facts, we attempted to theoretically explain and to demonstrate the possibilities of TDGA formation via different ways of homocysteine transformation. This scheme was used in evaluating the results obtained by testing urine of a woman suffering from impaired function of methionine synthase reductase (CblE type of homocystinuria). The amount of TDGA excreted in her morning urine was very sensitive to the changes in her treatment based upon a combination of N5-formyl tetrahydrofolate, betaine and vitamin B12. Vitamin B12 given in the evening either alone or together with betaine increased the TDGA excretion in the morning urine up to ten times. On the other hand, in the absence of vitamin B12, betaine in combination with N5-formyl tetrahydrofolate hindered the appearance of TDGA in the morning urine. Generally, the determination of TDGA in urine of an appropriately pretreated patient may indicate the degree of success of the treatment., T. Navrátil, M. Petr, Z. Šenholdová, K. Přistoupilová, T. I. Přistoupil, M. Heyrovský, D. Pelclová, E. Kohlíková., and Obsahuje bibliografii a bibliografické odkazy
A voltammetric technique was used (differential pulse voltammetry with a carbon fibre microelectrode) to investigate dynamics of the changes of catecholamine overflow in the corpus striatum following electroconvulsive stimulation (ECS) of chloral hydrate-anaesthetized rats. Application of "maximal" ECS (50 Hz, AC, sine wave, approximately 150 mA, 0.2 s) caused large enhancement of catechol-oxidative current (CA.OC): In the first minute after its arrest, the CA.OC peak raised to 1032±405% (n=5, mean±S.D.) of the controls (P<0.001, Student's t-test). This large elevation of the extracellular catecholamine content ceased rapidly - the baseline level was attained in the second minute. CA.OC changes evoked by a "minimal" ECS (50 Hz, AC, sine wave, approximately 30 mA, 0.2 s) were equivocal in the first minute (increase, decrease: 145 ±56 %, P>0.05, n=6). Possible mechanisms of the ECS therapeutic effect are discussed.
The administration of creatine (5 g/day for one month) to 11 young active sportsmen affected their urinary excretion of creatine, creatinine, and thiodiglycolic acid (TDGA) as well as blood levels of homocysteine, vitamin B12 and folates. The probands were divided into four groups, according to the amount of creatine found in urine, and of folates and vitamin B12 determined in blood. The changes of folates and vitamin B12 were mutually reciprocal. Each group utilized CR as donor of one- and two-carbon (1C and 2C) units by means of homocysteine (HoCySH), folates, and vitamin B12, in different metabolic pathways. In 10 men the creatine administration was accompanied by an increase of HoCySH level in blood, while in the last man, with accidentally discovered hyperhomocysteinemia, the HoCySH level dropped by 50 %. Differences between initial and terminal TDGA levels indicate that creatine affects equilibria of redox processes. Creatinine excretion into urine changed in the dependence on the extent of metabolic disturbances., T. Navrátil ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Using a microelectrode with carbon filaments and the voltammctric technique, changes evoked in the catechol oxidation current (CA.OC) and multiple unit activity (MUA) by microinjection of 3-5 ¿ri 03 mol.I'1 KC1 were studied in the reticular formation (RF) of the medulla oblongata of anaesthetized rats; the effect of KC1 stimulation of the RF and corpus striatum (S) on the CA.OC in these structures was compared. The microinjection of KC1 in the vicinity of the working electrode in the RF caused depression of MUA which began 2-3 s after administration, persisted for up to 6 min after and then diminished, reaching control values within 9 min. The voltammctric signal was first recorded in the 1st min after microinjection, when there was an evident decrease in the CA.OC value (59 % of the control value); this effect reached its maximum 7 min after administration (a mean drop to 23 % of the control), while at the end of the experiment (i.e. after 24 min) CA.OC values had risen to 45-80 % of the control value. The response in the S had a biphasic character, however. Immediately after the microinjection (1st min), the mean CA.OC value rose to 626 % of the control, while in the second phase (3-10 min) it was seen to fall below the control values (means 21-63 % of the control). The differences in the changes evoked by K+ depolarization in the concentration of catecholamines in the RF and S microenvironment are discussed from the aspect of the existence of different pools of the transmitter and
other regional differences. The possibility of a relationship between considered.